卡马克算法-代码研究

//@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@




//@ CIRCULAR DIRTY BUFFER CIRCULAR DIRTY BUFFER CIRCULAR DIRTY BUFFER




//@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@








static int _oldLevelX;




static int _oldLevelY;




static int _lastTileX;




static int _lastTileY;








static int _vp_x;




static int _vp_y;




static int _vp_w;




static int _vp_h;








static Image _imgCDB;




static Graphics _gCDB;














static void CDB_Init() ...{




_imgCDB = Image.createImage(DEF.CDB_W, DEF.CDB_H);




_gCDB = _imgCDB.getGraphics();








_lastTileX = -1;




_lastTileY = -1;








_oldLevelX = -1;




_oldLevelY = -1;








_vp_x = DEF.SV_X;




_vp_y = DEF.SV_Y;








_vp_w = DEF.SV_W;




_vp_h = DEF.SV_H;




}










static void CDB_Free() ...{




_gCDB = null;




_imgCDB = null;




}










/**/////////////////////////////////////////////////////////////////////////////////////////////////////














static void CDB_UpdateGameView(int x, int y) ...{




int lx = x >> 4; // x / GAME.G_TILE_W;




int ly = y >> 4; // y / GAME.G_TILE_H;








int olx = _oldLevelX >> 4; // _oldLevelX / GAME.G_TILE_W;




int oly = _oldLevelY >> 4; // _oldLevelY / GAME.G_TILE_H;










if ((lx == _lastTileX) && (ly == _lastTileY)) ...{




_oldLevelX = x;




_oldLevelY = y;




return;




}








if ((_lastTileX == -1 && _lastTileY == -1) ||






(Abs(lx - olx) >= DEF.CDB_TW) || (Abs(ly - oly) >= DEF.CDB_TH)) ...{




CDB_InvalidateTiles(lx, ly, lx + DEF.CDB_TW, ly + DEF.CDB_TH);






} else ...{




int minX, maxX, minY, maxY;




int x1, x2, y1, y2;








minX = ((x >= _oldLevelX) ? olx : lx);




minY = ((y >= _oldLevelY) ? oly : ly);




maxX = lx + olx - minX;




maxY = ly + oly - minY;








x1 = (_oldLevelX < x) ? (minX + DEF.CDB_TW) : minX;




x2 = (x1 - minX + maxX);










if (x1 == x2) ...{






if (x > _oldLevelX) ...{




x1--;






} else if (x < _oldLevelX) ...{




x2++;




}




}








y1 = (_oldLevelY <= y) ? maxY : minY;




y2 = y1 + DEF.CDB_TH;








CDB_InvalidateTiles(x1, y1, x2, y2);








x1 = maxX;




x2 = minX + DEF.CDB_TW;








y1 = (_oldLevelY < y) ? (minY + DEF.CDB_TH) : minY;




y2 = (_oldLevelY < y) ? (maxY + DEF.CDB_TH) : maxY;










if (y1 == y2) ...{






if (y > _oldLevelY) ...{




y1--;






} else if (y < _oldLevelY) ...{




y2++;




}




}








CDB_InvalidateTiles(x1, y1, x2, y2);




}








// record level coords (for not redrawin every time ...)




_lastTileX = lx;




_lastTileY = ly;








_oldLevelX = x;




_oldLevelY = y;








}










/**/////////////////////////////////////////////////////////////////////////////////////////////////////




// Repaint a portion of game background into the circular dirty buffer










static void CDB_InvalidateTiles(int minX, int minY, int maxX, int maxY) ...{




int x, y;








if (maxX > map_sizeX)




maxX = map_sizeX;




if (maxY > map_sizeY)




maxY = map_sizeY;








if (minX == maxX || minY == maxY)




return;








_gCDB.setClip(0, 0, DEF.CDB_W, DEF.CDB_H);










for (x = minX; x < maxX; x++) ...{






for (y = minY; y < maxY; y++) ...{




int t = x + y * map_sizeX;




int x1 = (x * DEF.TILE_W) % DEF.CDB_W;




int y1 = (y * DEF.TILE_H) % DEF.CDB_H;








DrawTile(_gCDB, t, x1, y1);








}




}








}














/**/////////////////////////////////////////////////////////////////////////////////////////////////////




// CDB -> Screen










static void CDB_DrawGameView() ...{




int bb_pos_x = (s_camX % DEF.CDB_W);




int bb_pos_y = (s_camY % DEF.CDB_H);








int widthR = (DEF.CDB_W - bb_pos_x);




int widthL = (DEF.CDB_W - widthR);




int heightB = (DEF.CDB_H - bb_pos_y);




int heightT = (DEF.CDB_H - heightB);








// blit backbuffer on screen ...




// ************* top left *************




CDB_Copy2Screen(DEF.SV_X, DEF.SV_Y, widthR, heightB,




DEF.SV_X - bb_pos_x, DEF.SV_Y - bb_pos_y);




// ************* top right *************




CDB_Copy2Screen(DEF.SV_X + widthR, DEF.SV_Y, widthL, heightB,




DEF.SV_X + widthR, DEF.SV_Y - bb_pos_y);




// ************* bottom left *************




CDB_Copy2Screen(DEF.SV_X, DEF.SV_Y + heightB, widthR, heightT,




DEF.SV_X - bb_pos_x, DEF.SV_Y + heightB);




// ************* bottom right *************




CDB_Copy2Screen(DEF.SV_X + widthR, DEF.SV_Y + heightB, widthL, heightT,




DEF.SV_X + widthR, DEF.SV_Y + heightB);




}










/**/////////////////////////////////////////////////////////////////////////////////////////////////////








private static void CDB_Copy2Screen(int x, int y, int w, int h, int xx,






int yy) ...{








//clip viewport






if (x < _vp_x) ...{




w = w - _vp_x + x;




x = _vp_x;




}






if (y < _vp_y) ...{




h = h - _vp_y + y;




y = _vp_y;




}






if (x + w > _vp_x + _vp_w) ...{




w = _vp_x + _vp_w - x;




}






if (y + h > _vp_y + _vp_h) ...{




h = _vp_y + _vp_h - y;




}








if (w <= 0 || h <= 0)




return;












s_g.setClip(x, y, w, h);




s_g.drawImage( _imgCDB, xx, yy, Graphics.LEFT | Graphics.TOP);




}